Boeing is focussing its attention on a new narrowbody aircraft, as it characterises the response to its 737 re-engining plans as "underwhelming".

Mike Bair, VP of Advanced 737 Product Development, says as the company moves closer to announcing at June's Paris air show if it intends to pursue re-engining or a clean-sheet design, the airframer must begin to configure a new offering to meet the demands of the marketplace for a 2019 or 2020 entry into service.

Airline and industry officials confirm that Boeing is sounding out opinions on a "grab-bag" of technologies and possible configurations including a six or seven-abreast cross-section, possible composite wing and fuselage, fly-by-wire flight control system and advance pneumatic bleed air system.

But despite these potential advances, Bair says the aircraft will not have a revolutionary appearance: "These are going to be conventional looking engines and they're going to be conventional looking airplanes. Tube and wing has been around for a long time for lots of really good reasons. It's very, very efficient way to fly stuff around, especially people."

Bair says Boeing plans to settle on one cross-section for its new family of aircraft, slotted below its 210-250 seat 787-8, with ideally a choice of two engines, a departure from an exclusivity agreement the airframer has with CFM International on its 737s today.

"Our sort of fundamental assumption is that we would provide a choice," though Bair adds, "If there's reasons you have an opportunity where a sole source makes sense, then you evaluate it."

Boeing is working closely with CFM, Rolls-Royce and Pratt & Whitney to identify the airframer's engine options for a new jet. "All three of them have given us what they think they can do for an engine that comes into service in [2019 or 2020], and it's better than what they could do for a [2015 or 2016 entry into service]," he says, an allusion to improved performance compared to the Bombardier CSeries and Airbus A320neo.

Once the proper market for the new aircraft is identified, Boeing will determine if the 787's composites and systems scale down to a smaller package. A composite transition would likely require a significantly different industrial footprint as carbon fibre winding machine investment is significantly different from the metallic manufacturing assembly techniques used on today's 737s.

Bair envisions the current 737 assembly line living on for some time, as Boeing forecasts a large installed base operating large fleets at the end of the decade. "There are going to be a lot of operators that are going to say, I just need another 20 or 30 or 40 and that can go on for quite a while. There's a very large probability that there's going to be a very long overlap."

Source: Air Transport Intelligence news